1. Field of the Invention
The present invention relates to a wireless communication system, a communication device, a communication controlling method, and a communication control program for effecting transmission and reception of data in a connection mode (ad hoc network) configured by wireless terminals (stations) without the use of a relay device (access point). More particularly, the present invention concerns a wireless communication system, a communication device, a communication controlling method, and a communication control program which make it possible to automate the setting unique to a wireless LAN.
2. Description of the Related Art
In recent years, a wireless LAN is known as a technique in which a plurality of terminals such as PCs (personal computers), PDAs (personal digital assistants), and a printer are connected by wireless links to structure a LAN (local area network). IEEE 802.11 (IEEE 802.11a/b/g) is known as one standard for it.
The most basic component elements which make up a wireless LAN by this IEEE 802.11 standard include an ad hoc network which is configured only by wireless terminals (stations) and an infrastructure network in which communication is effected between stations or with a device on a wired LAN by the use of a relay device (access point).
In a case where a wireless LAN is connected, it is necessary to carry out in advance the setting unique to the wireless LAN, including an SSID (service set identifier) as authentication, WEP (wired equivalent privacy), and the like.
As a technique for automatically executing the setting for wireless LAN connection without requiring the operation of these special settings, “Communication device and method, recording medium, and program” is disclosed in Japanese Patent Application Laid-Open No. 2003-229872.
In the invention in this Japanese Patent Application Laid-Open No. 2003-229872, reference is made to a technique in which a station reads local network information recorded on an IC (integrated circuit) card and executes the network setting in accordance with the information, thereby making it possible to automatically effect the setting for wireless connection without requiring special setting operation by a user.
However, with the invention in Japanese Patent Application Laid-Open No. 2003-229872, there has been a problem in that it is necessary to prepare a recording medium such as an IC card for storing the network setting and a reader for reading the setting from the IC card.
Conventionally, in a network configured by the wireless LAN, although there are advantages that there is no encumbrance of the troublesome cable (cableless) and that the installation or movement of the terminal is free, the complicatedness of the setting operation and fragility in security have been problems.
As functions for strengthening security in the wireless LAN, it is largely possible to cite two kinds: (a) access control and (b) encryption of data.
For instance, the former functions (a) include MAC (media access control) address filtering function, the user authentication function by a RADIUS (remote authentication dial-in user service) server, and the like. In the case of the MAC address registration, however, since the MAC address is described in plain text on a wireless frame, the MAC address can be easily acquired by using a tool, so that spoofing becomes possible.
In addition, in the case where the RADIUS server is used, a user who connected to an access point is authenticated by the RADIUS server, and a determination is made as to whether or not an access is allowed. Hence, this method cannot be applied to the ad hoc network.
On the other hand, the latter functions (b) include, among others, encryption based on WEP. WEP adopts an encryption algorithm of RC4 (Ron's Code 4) and has the function of preventing data concealment, tampering, forgery, spoofing, and the like. However, unless a WEP key is changed after it has been set manually, all the stations repeat connection and authentication by using the same key, so that there is a possibility that a willful user may obtain the WEP key in an unauthorized way and use the WEP key by stealth by making the most use of cryptography.
In addition, it is possible to cite a method in which an IP packet during communication is encrypted by IPsec (IP security) or the like, but in this case there is the problem of an increased processing burden for the station.
Accordingly, the present invention has been devised in view of the above-described problems, and its object is to provide a wireless communication system, a communication device, a communication controlling method, and a communication control program in which the setting unique to a wireless LAN is automatically effected between stations during the establishment of a session.